SkPerlinNoiseShader::CreateTubulenceNoise() is misspelled

Add missing 'r'.

BUG=skia:2329
R=bsalomon@google.com, hcm@google.com, sugoi@chromium.org

Author: siglesias@igalia.com

Review URL: https://codereview.chromium.org/207543008

git-svn-id: http://skia.googlecode.com/svn/trunk@14008 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/AUTHORS b/AUTHORS
index 0e8abcc..de3fa4d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -15,6 +15,7 @@
 ARM <*@arm.com>
 George Wright <george@mozilla.com>
 Google Inc. <*@google.com>
+Igalia <*@igalia.com>
 Intel <*@intel.com>
 Jacek Caban <cjacek@gmail.com>
 NVIDIA <*@nvidia.com>